a direct or indirect payment, economic concession, or privilege granted by a government to private firms, households, or other governmental units in order to promote a public objective. Identification of a subsidy is often complicated because of the variety of subsidy instruments, the multiplicity of the objectives they are designed to serve, and the complexity of their effects.

Subsidies to transportation, housing, agriculture, mining, and other industries have been instituted on the grounds that preservation or expansion of these industries, even at a cost to the general public, is in the public interest. Subsidies to the arts, sciences, humanities, and religion have also been instituted in many nations because of the inability of the private economy to support these functions at a level consistent with public policy.

The term also includes grants of money or other aid (social welfare program) made by a central government to a local one to promote objectives in which the central government has an interest (e.g., grants-in-aid). More broadly defined, subsidies include welfare payments designed to ameliorate inequalities in the distribution of income and also other governmental programs designed to mitigate the effects of market forces.

Regardless of the form that subsidies take, their purpose is to alter the results created by otherwise free markets and unimpeded competition in a direction considered more consistent with the objectives of public policy. The effect of subsidies is to encourage the growth of subsidized industries relative to industries that do not receive subsidies and thus to alter the uses to which an economy puts its resources.

Subsidies have a long history in all nations. They were extensively employed by governments during the mercantilist period preceding the Industrial Revolution, when it was thought that the accumulation of gold through a favourable balance of trade required the protection of domestic manufacturers. Such protectionist doctrines have often been viewed with skepticism. Nevertheless, protectionism continues as a part of national economic policy in most nations of the world. In nations in which a strong central government influences the price and production policies of domestic industries, the subsidy device is replaced by comprehensive economic planning.

Subsidies are implemented through a variety of financial techniques, such as (1) direct payments in cash or kind, (2) governmental provision of goods or services at prices below the normal market price, (3) governmental purchase of goods or services at prices in excess of the market price, and (4) tax concessions and similar inducements. In addition, there are numerous governmental policies that have subsidy effects, such as regulatory statutes that soften the full force of competition, policies that require the purchase of goods from favoured producers or nations, and protective wage and price legislation.

A distinction is sometimes made between direct, or visible, subsidies (such as direct payments for ship construction and airline operation), which are easy to identify and measure, and indirect, or concealed, subsidies (such as price ceilings or floors, tariffs, and tax concessions), which are difficult to identify and always difficult to measure. Historically, direct subsidies have been used most widely to promote the development of the transportation industries. All nations have viewed ocean shipping and aviation as important instruments of defense and foreign policy, and the development of land transportation has been considered a prerequisite for domestic economic development. Indirect subsidies arise when governments buy directly from private producers at higher-than-market prices (price), maintain higher prices through manipulation of markets, provide services to private enterprises at prices below the cost of providing the service, or grant special tax concessions.

Although subsidies are initiated and justified in terms of benefits to the general public, they result in either a higher level of general taxation or higher prices for consumer goods. They may also encourage the preservation of inefficient producers. The test of the desirability of a subsidy hinges on a comparison of the public benefits (which are usually diffuse and difficult to measure) with their costs in terms of higher prices, taxes, and inefficiency.